Hi all:

I downloaded a test version of ddd and was trying to install it. An error shown as below jumped out:

configure: error: The Motif include file "Xm/Xm.h" could not be found. Please use the configure options '--with-motif-includes=DIR' and '--with-motif-libraries=DIR' to specify the Xm location.

So confused. I do not know what this Xm.h is or where to find it.

Any help is deeply appreciated.